Ultrasonic clamp coagulator apparatus having force limiting clamping mechanism

ABSTRACT

An ultrasonic surgical clamp coagulator apparatus is configured to effect cutting, coagulation, and clamping of tissue by cooperation of a clamping mechanism of the apparatus with an associated ultrasonic end-effector. In order to limit the force with which tissue is clamped between a clamp arm of the clamping mechanism and the end-effector, the clamping mechanism includes a force-limiting spring which operatively connects an operating lever of the apparatus and components of the clamp drive mechanism. The force-limiting spring is preferably pre-loaded so that the interconnection of the associated components is desirably &#34;stiff&#34;, thus providing a user with good tactile feedback during operation of the clamping mechanism. At least one travel stop is preferably provided on the apparatus housing for limiting movement of the operating lever after a predetermined degree of relative movement of the operating components in opposition to the force-limiting spring.

TECHNICAL FIELD

The present invention relates generally to ultrasonic surgical devices,and more particularly to an ultrasonic surgical clamp coagulatorapparatus for coagulating and/or cutting tissue, including a clampingmechanism having an arrangement for preventing application of excessiveclamping force to tissue gripped by the mechanism.

BACKGROUND OF THE INVENTION

Ultrasonic surgical instruments are finding increasingly widespreadapplications in surgical procedures by virtue of the unique performancecharacteristics of such instruments. Depending upon specific instrumentconfigurations and operational parameters, ultrasonic surgicalinstruments can provide substantially simultaneous cutting of tissue andhemostasis by coagulation, desirably minimizing patient trauma. Thecutting action is typically effected by an end-effector at the distalend of the instrument, with the end-effector transmitting ultrasonicenergy to tissue brought into contact therewith. Ultrasonic instrumentsof this nature can be configured for open surgical use, or laparoscopicor endoscopic surgical procedures.

Ultrasonic surgical instruments have been developed that include a clampmechanism to press tissue against the end-effector of the instrument inorder to couple ultrasonic energy to the tissue of a patient. Such anarrangement (sometimes referred to as an ultrasonic transector) isdisclosed in U.S. Pat. No. 5,322,055, hereby incorporated by reference.

One important design parameter in providing a ultrasonic clampcoagulator or similar apparatus is configuring the device to preventapplication of excessive clamping force, while maintaining good tactilefeedback for the user of the instrument. In some previous constructions,no specific mechanism has been provided for limiting clamping forces,with forces thereby typically limited only by flexure of the components,rigid travel stops on the force input lever of the construction, thespecific mechanical advantage provided by the configuration of thedevice, and the hand strength of the user. Experience has shown that itis important to provide a consistent clamping force in an ultrasonicdevice in order to create the maximum tissue effect without overloadingthe system, again while providing good tactile feedback.

Commercial embodiments of the clamping apparatus disclosed in theabove-referenced patent have included a reciprocable elongated wire-likeelement for transmitting movement from the operating lever of the deviceto the pivotal clamp arm of the clamping mechanism. It has been foundthat this arrangement inherently limits the force transmitted from thehandle to the clamping mechanism. It is believed that the wire-likeelement is substantially unconfined along a substantial portion of itslength, and due to the resilient flexibility of the wire-like elementand associated elements and linkages, the device functions to limitforce transmitted from the handle to the associated clamp arm. Inparticular, it is believed that the wire-like element is loaded incompression when driven to close the associated clamp arm. If excessiveforce is applied to the wire-like element, it is believed to deflect, ina column-like fashion, to limit the clamping force transmittedtherethrough.

As will be recognized, variations in the grip strength of users of anultrasonic clamp can result in large variations in the maximum clampingforce which is applied to tissue at the end-effector. Excessive clampingforce can cause overloading of the ultrasonic system, which canundesirably dampen the acoustic motion of the system and reduce thetissue effect. If a clamping mechanism is designed with a low mechanicaladvantage, to thereby limit the clamping force, some users may befatigued quickly during use of the device, and experience difficulty inapplying sufficient force at the operating lever to create sufficientclamping force at the end-effector. If clamping force is insufficient,the grasping capability of the instrument is undesirably limited, andthe desired tissue effect may not be achieved.

Some previous ultrasonic clamp constructions formed from relativelystiff components exhibit desirable tactile feedback, but are notconfigured to limit clamping forces. In contrast, some devices have beenconstructed with components which can flex attendant to application ofclamping force, which acts to limit clamping force, but does not providethe desired tactile feedback to the user due to the resultant "spongy"feel of the instrument. Such arrangements ordinarily are not configuredto indicate when the maximum useable clamping force has been applied. Asa consequence, a user may continue to apply additional force against atravel stop for the operating lever, not appreciating that additionalclamping force is not being created, and creating user fatigue.

The present invention is directed to an ultrasonic clamp coagulatorapparatus having a force-limiting clamp mechanism to limit the clampingforce applied thereby, while still providing desirably good tactilefeedback for a user.

SUMMARY OF THE INVENTION

An ultrasonic surgical clamp coagulator apparatus embodying theprinciples of the present invention is configured to permit selectivecutting, coagulation, and clamping of tissue during surgical procedures.In order to desirably limit the force applied to tissue by the clampingmechanism, while maintaining good tactile feedback for a user, the clampmechanism of the apparatus includes a force-limiting arrangement,including a pre-loaded spring. By virtue of the pre-loaded spring, theoperating mechanism exhibits a desirably "stiff" and firm feel, therebyproviding good tactile feedback and control over the clamping force. Inthe event that excessive force is applied to the operating mechanism bythe user, components of the operating mechanism are movable relative toeach other, in opposition to the pre-load spring. At least one travelstop is preferably provided for limiting movement of the operating leverprior to a predetermined degree of relative movement (in opposition tothe pre-load spring) of the components of the operating mechanism.

In accordance with the illustrated embodiment, the present ultrasonicclamp coagulator apparatus includes a housing, and an outer tubularsheath having a proximal end rotatably joined to the housing. An inner,preferably tubular actuating member is reciprocably positioned withinthe outer tubular sheath for rotation therewith with respect to theapparatus housing. An ultrasonic waveguide is positioned within theouter tubular sheath, and includes an end-effector extending distally ofa distal end of the outer tubular sheath.

Clamping of tissue against the end-effector is achieved by a clampmechanism including a clamp arm pivotally mounted on the distal end ofthe outer tubular sheath of the apparatus. Pivotal movement of the clamparm with respect to the end-effector permits tissue to be clampedtherebetween. The clamp arm is operatively connected with the actuatingmember so that reciprocable movement of the actuating member pivotallymoves the clamp arm with respect to the end-effector.

An operating lever is pivotally mounted on the housing, with theapparatus including a clamp drive mechanism operatively interconnectingthe operating lever with the actuating member. By this construction,pivotal movement of the operating lever reciprocably moves the actuatingmember, thereby pivotally moving the clamp arm.

The clamp drive mechanism includes a drive collar joined to theactuating member, and a drive yoke which is operatively joined to theoperating lever, and which engages the drive collar. Force transmittedfrom the operating lever to the clamp arm by the actuating member islimited by the provision of a pre-load spring which operativelyinterconnects the operating lever and the drive yoke. In particular, oneof the operating lever and the drive yoke define a spring cage, with theother defining a spring slot positioned adjacent to the spring cage. Apre-load spring is held captive within the spring cage, and ispositioned within the spring slot to thereby transmit and limit forcetransmitted from the operating lever to the drive yoke. In the preferredconstruction, the drive yoke and operating lever are mounted for pivotalmovement about a common housing pivot, with relative pivotal movement ofthe drive yoke with respect to the operating lever taking place inopposition to the pre-load spring.

By this arrangement, the spring acts to pre-load the operativeconnection of the drive yoke and operating lever, with these componentsordinarily pivoting as a unit with respect to their common housingpivot. However, in the event that excessive force is applied by a userto the operating lever, force transmitted to the clamp arm is limited byrelative movement of the operating lever with respect to the drive yokein opposition to the pre-load spring.

In the illustrated embodiment, the drive yoke defines the spring cage ofthe mechanism, with the operating lever preferably including abifurcated portion having a pair of spring flanges, each defining aspring slot, positioned on respective opposite sides of the spring cage.The pre-load spring preferably comprises a compression coil springpositioned within the spring cage, as well as within the spring slots ofthe pair of spring flanges. The illustrated construction permitsrelative pivotal movement of the operating lever and drive yoke, inopposition to the coil spring, in either direction.

The clamp apparatus preferably includes a travel stop engageable by theoperating lever prior to a predetermined degree of movement of theoperating lever relative to the drive yoke. By this preferredarrangement, the operating lever engages the travel stop, thuspreventing the input of any more clamping force into the clampmechanism, prior to full compression of the coil spring of theforce-limiting arrangement.

Other features and advantages of the present invention will becomereadily apparent from the following detailed description, theaccompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an ultrasonic surgical system includingan ultrasonic clamp coagulator apparatus embodying the principles of thepresent invention;

FIG. 2 is an enlarged, fragmentary perspective view of a clamp mechanismof the clamp coagulator apparatus illustrated in FIG. 1;

FIG. 3 is a side elevational view, partially in cut-away, of the clampcoagulator embodying the principles of the present invention, shown inoperative association with an ultrasonic drive unit of the surgicalsystem shown in FIG. 1;

FIG. 4 is an exploded view of the ultrasonic surgical clamp coagulatorapparatus embodying the principles of the present invention;

FIG. 5 is an enlarged, fragmentary view of the present clamp coagulatorapparatus illustrating a clamp drive mechanism thereof and associateddetent mechanism;

FIG. 6 is a diagrammatic view further illustrating the clamp drivemechanism and detent mechanism of the present clamp coagulatorapparatus;

FIG. 7 is a diagrammatic view of the detent mechanism of the presentinvention;

FIG. 8 is a perspective view of a clamp mechanism drive collar of thepresent clamp coagulator apparatus; and

FIGS. 9-11 are diagrammatic views illustrating operation of theforce-limiting arrangement of the clamp mechanism of the presentinvention.

DETAILED DESCRIPTION

While the present invention is susceptible of embodiments in variousforms, there is shown in the drawings and will hereinafter be describeda presently preferred embodiment, with the understanding that thepresent disclosure is to be considered as an exemplification of theinvention, and is not intended to limit the invention to the specificembodiment illustrated.

The present invention is particularly directed to an improved ultrasonicsurgical clamp coagulator apparatus which is configured for effectingtissue cutting, coagulation, and/or clamping during surgical procedures.The present apparatus can readily be configured for use in both opensurgical procedures, as well as laparoscopic or endoscopic procedures.Versatile use is facilitated by selective use of ultrasonic energy. Whenultrasonic components of the apparatus are inactive, tissue can bereadily gripped and manipulated, as desired, without tissue cutting ordamage. When the ultrasonic components are activated, the apparatuspermits tissue to be gripped for coupling with the ultrasonic energy toeffect tissue coagulation, with application of increased pressureefficiently effecting tissue cutting and coagulation. If desired,ultrasonic energy can be applied to tissue without use of the clampingmechanism of the apparatus by appropriate manipulation of the ultrasonic"blade" or end-effector of the device.

As will become apparent from the following description, the presentclamp coagulator apparatus is particularly configured for disposable useby virtue of its straightforward construction. As such, it iscontemplated that the apparatus be used in association with anultrasonic drive unit of a surgical system, whereby ultrasonic energyfrom the drive unit provides the desired ultrasonic actuation of thepresent clamp coagulator apparatus. It will be appreciated that a clampcoagulator apparatus embodying the principles of the present inventioncan be configured for non-disposable use, and non-detachably integratedwith an associated ultrasonic drive unit. However, detachable connectionof the present clamp coagulator apparatus with an associated ultrasonicdrive unit is presently preferred for single-patient use of theapparatus.

With reference first to FIGS. 1 and 3, therein is illustrated apresently preferred embodiment of a surgical system, generallydesignated 10, which includes an ultrasonic clamp coagulator apparatusembodying the principles of the present invention. Preferred details ofthe ultrasonic generator and associated ultrasonic drive unit of thesurgical system 10 will first be described, with subsequent detaileddescription of the ultrasonic surgical clamp coagulator apparatus,including a clamp mechanism configured for indexed rotation, embodyingthe principles of the present invention.

The surgical system 10 includes an ultrasonic generator 30 and anassociated ultrasonic surgical instrument. The surgical instrumentincludes an ultrasonic drive unit, designated 50, and an ultrasonicclamp coagulator apparatus 120 embodying the principles of the presentinvention. As will be further described, an ultrasonic transducer of thedrive unit 50, and an ultrasonic waveguide of the clamp coagulator 120,together provide an acoustic assembly of the present surgical system,with the acoustic assembly providing ultrasonic energy for surgicalprocedures when powered by generator 30. It will be noted that in someapplications, the ultrasonic drive unit 50 is referred to as a "handpiece assembly" because the surgical instrument of the surgical systemis configured such that a surgeon grasps and manipulates the ultrasonicdrive unit 50 during various procedures and operations. The clampcoagulator apparatus 120 embodying the principles of the presentinvention preferably includes a scissors-like grip arrangement whichfacilitates positioning and manipulation of the instrument apart frommanipulation of the ultrasonic drive unit 50.

The generator 30 of the surgical system sends an electrical signalthrough a cable 32 at a selected excursion, frequency, and phasedetermined by a control system of the generator 30. As will be furtherdescribed, the signal causes one or more piezoelectric elements of theacoustic assembly of the surgical instrument to expand and contract,thereby converting the electrical energy into mechanical motion. Themechanical motion results in longitudinal waves of ultrasonic energythat propagate through the acoustic assembly in an acoustic standingwave to vibrate the acoustic assembly at a selected frequency andexcursion. An end-effector at the distal end of the waveguide of theacoustic assembly is placed in contact with tissue of the patient totransfer the ultrasonic energy to the tissue. As further describedbelow, a surgical tool, such as, a jaw or clamping mechanism, ispreferably utilized to press the tissue against the end-effector.

As the end-effector couples with the tissue, thermal energy or heat isgenerated as a result of friction, acoustic absorption, and viscouslosses within the tissue. The heat is sufficient to break proteinhydrogen bonds, causing the highly structured protein (i.e., collagenand muscle protein) to denature (i.e., become less organized). As theproteins are denatured, a sticky coagulum forms to seal or coagulatesmall blood vessels. Deep coagulation of larger blood vessels resultswhen the effect is prolonged.

The transfer of the ultrasonic energy to the tissue causes other effectsincluding mechanical tearing, cutting, cavitation, cell disruption, andemulsification. The amount of cutting as well as the degree ofcoagulation obtained varies with the excursion of the end-effector, thefrequency of vibration, the amount of pressure applied by the user, thesharpness of the end-effector, and the coupling between the end-effectorand the tissue.

As illustrated in FIG. 1, the generator 30 includes a control systemintegral with the generator 30, a power switch 34, and a triggeringmechanism 36. The power switch 34 controls the electrical power to thegenerator 30, and when activated by the triggering mechanism 36, thegenerator 30 provides energy to drive the acoustic assembly of thesurgical system 10 at a predetermined frequency and to drive theend-effector at a predetermined excursion level. The generator 30 drivesor excites the acoustic assembly at any suitable resonant frequency ofthe acoustic assembly.

When the generator 30 is activated via the triggering mechanism 36,electrical energy is continuously applied by the generator 30 to atransducer stack or assembly 40 of the acoustic assembly. A phase-lockedloop in the control system of the generator 30 monitors feedback fromthe acoustic assembly. The phase lock loop adjusts the frequency of theelectrical energy sent by the generator 30 to match the resonantfrequency of the selected longitudinal mode of vibration of the acousticassembly including the tissue load. In addition, a second feedback loopin the control system maintains the electrical current supplied to theacoustic assembly at a preselected constant level in order to achievesubstantially constant excursion at the end-effector of the acousticassembly.

The electrical signal supplied to the acoustic assembly will cause thedistal end of the waveguide, i.e., the end-effector, to vibratelongitudinally in the range of, for example, approximately 20 kHz to 250kHz, and preferably in the range of about 54 kHz to 56 kHz, and mostpreferably at about 55.5 kHz. The excursion of the vibrations at theend-effector can be controlled by, for example, controlling theamplitude of the electrical signal applied to the transducer assembly 40of the acoustic assembly by the generator 30.

As noted above, the triggering mechanism 36 of the generator 30 allows auser to activate the generator 30 so that electrical energy may becontinuously supplied to the acoustic assembly. The triggering mechanism36 preferably comprises a foot activating switch that is detachablycoupled or attached to the generator 30 by a cable or cord.Alternatively, the triggering mechanism can be configured as a handswitch incorporated in the ultrasonic drive unit 50 to allow thegenerator 30 to be activated by a user.

The generator 30 also has a power line 38 for insertion in anelectro-surgical unit or conventional electrical outlet. It iscontemplated that the generator 30 can also be powered by a directcurrent (DC) source, such as a battery. The generator 30 can compriseany suitable generator, such as Model No. GENO1, available from EthiconEndo-Surgery, Inc.

Referring to FIGS. 1 and 3, the ultrasonic drive unit 50 of the surgicalinstrument includes a multi-piece housing 52 adapted to isolate theoperator from the vibrations of the acoustic assembly. The drive unithousing 52 can be shaped to be held by a user in a conventional manner,but it is contemplated that the present clamp coagulator 120 principallybe grasped and manipulated by a scissors-like arrangement provided by ahousing of the apparatus, as will be described. While the multi-piecehousing 52 is illustrated, the housing 52 may comprise a single orunitary component.

The housing 52 of the ultrasonic drive unit 50 generally includes aproximal end, a distal end, and a cavity extending longitudinallytherein. The distal end of the housing 52 includes an opening 60configured to allow the acoustic assembly of the surgical system 10 toextend therethrough, and the proximal end of the housing 52 is coupledto the generator 30 by the cable 32. The cable 32 preferably includesducts or vents 62 to allow air to be introduced into the housing 52 ofthe ultrasonic drive unit 50 to cool the transducer assembly 40 of theacoustic assembly.

The housing 52 of the ultrasonic drive unit 50 is preferably constructedfrom a durable plastic, such as Ultem®. It is also contemplated that thehousing 52 may alternatively be made from a variety of materialsincluding other plastics i.e. liquid crystal polymer (LCP), nylon, orpolycarbonate!. A suitable ultrasonic drive unit 50 is Model No. HP050,available from Ethicon Endo-Surgery, Inc.

The acoustic assembly of the surgical instrument generally includes afirst acoustic portion and a second acoustic portion. The first acousticportion is preferably carried by the ultrasonic drive unit 50, and thesecond acoustic portion (in the form of a waveguide and end-effector, aswill be described) is carried by the ultrasonic clamp coagulatorapparatus. The distal end of the first acoustic portion is operativelycoupled to the proximal end of the second acoustic portion preferably bya threaded connection.

As shown in FIG. 3, the first acoustic portion includes the transducerstack or assembly 40 and a mounting device 84, and the second acousticportion includes a transmission component or working member, referred toherein as a waveguide having an end-effector.

The components of the acoustic assembly are preferably acousticallytuned such that the length of each component is an integral number ofone-half wavelengths (nλ/2), where the wavelength λ is the wavelength ofa preselected or operating longitudinal vibration frequency f₀ of theacoustic assembly, and n is any non-negative integer. It is alsocontemplated that the acoustic assembly may incorporate any suitablearrangement of acoustic elements.

The transducer assembly 40 of the acoustic assembly converts theelectrical signal from the generator 30 into mechanical energy thatresults in longitudinal vibratory motion of the end-effector atultrasonic frequencies. When the acoustic assembly is energized, avibratory motion standing wave is generated through the acousticassembly. The excursion of the vibratory motion at any point along theacoustic assembly depends on the location along the acoustic assembly atwhich the vibratory motion is measured. A minimum or zero crossing inthe vibratory motion standing wave is generally referred to as a node(i.e., where motion is usually minimal), and an absolute value maximumor peak in the standing wave is generally referred to as an anti-node.The distance between an anti-node and its nearest node is one-quarterwavelength (λ/4).

As shown in FIG. 3, the transducer assembly 40 of the acoustic assembly,which is also known as a "Langevin stack", generally includes atransduction portion 90, a first resonator 92, and a second resonator94. The transducer assembly is preferably an integral number of one-halfsystem wavelengths (nλ/2) in length. It is to be understood that thepresent invention may be alternatively configured to include atransducer assembly comprising a magnetostrictive, electromagnetic orelectrostatic transducer.

The distal end of the first resonator 92 is connected to the proximalend of transduction section 90, and the proximal end of the secondresonator 94 is connected to the distal end of transduction portion 90.The first and second resonators 92 and 94 are preferably fabricated fromtitanium, aluminum, steel, or any other suitable material, and mostpreferably, the first resonator 92 is fabricated from 303 stainlesssteel and the second resonator 94 is fabricated from 7075-T651 Aluminum.The first and second resonators 92 and 94 have a length determined by anumber of variables, including the length of the transduction section90, the speed of sound of material used in the resonators 92 and 94, andthe desired fundamental frequency f₀ of the transducer assembly 40. Thesecond resonator 94 can be tapered inwardly from its proximal end to itsdistal end to function as a velocity transformer and amplify theultrasonic vibration excursion.

The transduction portion 90 of the transducer assembly 40 preferablycomprises a piezoelectric section of alternating positive electrodes 96and negative electrodes 98, with piezoelectric elements 100 alternatingbetween the electrodes 96 and 98. The piezoelectric elements 100 can befabricated from any suitable material, such as, for example, leadzirconate-titanate, lead metaniobate, lead titanate, or otherpiezoelectric material. Each of the positive electrodes 96, negativeelectrodes 98, and piezoelectric elements 100 have a bore extendingthrough the center. The positive and negative electrodes 96 and 98 areelectrically coupled to wires 102 and 104, respectfully. The wires 102and 104 transmit the electrical signal from the generator 30 toelectrodes 96 and 98.

As illustrated in FIG. 3, the piezoelectric elements 100 are held incompression between the first and second resonators 92 and 94 by a bolt106. The bolt 106 preferably has a head, a shank, and a threaded distalend. The bolt 106 is inserted from the proximal end of the firstresonator 92 through the bores of the first resonator 92, the electrodes96 and 98, and piezoelectric elements 100. The threaded distal end ofthe bolt 106 is screwed into a threaded bore in the proximal end ofsecond resonator 94. The bolt can be fabricated from steel, titanium,aluminum, or other suitable material and is preferably fabricated fromTi-6A1-4V Titanium, and most preferably from 4037 low alloy steel.

The piezoelectric elements 100 are energized in response to theelectrical signal supplied from the generator 30 to produce an acousticstanding wave in the acoustic assembly. The electrical signal causes anelectromagnetic field across the piezoelectric elements 100, causing thepiezoelectric elements 100 to expand and contract in a continuous manneralong the axis of the voltage gradient, producing high frequencylongitudinal waves of ultrasonic energy. The ultrasonic energy istransmitted through the acoustic assembly to the end-effector.

The mounting device 84 of the acoustic assembly has a proximal end, adistal end, and preferably has a length substantially equal to anintegral number of one-half system wavelengths. The proximal end of themounting device 84 is preferably axially aligned and coupled to thedistal end of the second resonator 94 by an internal threaded connectionnear an anti-node. (For purposes of this disclosure, the term "near" isdefined as "exactly at" or "in close proximity to".) It is alsocontemplated that the mounting device 84 may be attached to the secondresonator 94 by any suitable means, and the second resonator 94 andmounting device 84 may be formed as a single or unitary component.

The mounting device 84 is coupled to the housing 52 of the ultrasonicdrive unit 50 near a node. The mounting device 84 preferably includes anintegral mounting flange 108 disposed around its periphery. The mountingflange 108 is preferably disposed in an annular groove 110 formed in thehousing 52 of the ultrasonic drive unit 50 to couple the mounting device84 to the housing 52. A compliant member or material 112, such as a pairof silicone rubber O-rings attached by stand-offs, may be placed betweenthe annular groove 110 of the housing 52 and the integral flange 108 ofthe mounting device 86 to reduce or prevent ultrasonic vibration frombeing transmitted from the mounting device 84 to the housing 52.

The mounting device 84 is preferably secured in a predetermined axialposition by a plurality of pins 114, preferably four. The pins 114 aredisposed in a longitudinal direction ninety (90) degrees apart from eachother around the outer periphery of the mounting device 84. The pins 114are coupled to the housing 52 of the ultrasonic drive unit 50 and aredisposed through notches in the acoustic mounting flange 108 of themounting device 84. The pins 114 are preferably fabricated fromstainless steel.

The mounting device 84 is preferably configured to amplify theultrasonic vibration excursion that is transmitted through the acousticassembly to the distal end of the end-effector. In one preferredembodiment, the mounting device 84 comprises a solid, tapered horn. Asultrasonic energy is transmitted through the mounting device 84, thevelocity of the acoustic wave transmitted through the mounting device 84is amplified. It is contemplated that the mounting device 84 beconfigured as any suitable shape, such as, for example, a stepped horn,a conical horn, an exponential horn, a unitary gain horn, or the like.

As shown in FIG. 3, the mounting device 84 is preferably acousticallycoupled to the second acoustic portion of the ultrasonic clampcoagulator apparatus 120. The distal end of the mounting device 84 ispreferably coupled to the proximal end of the second acoustic portion byan internal threaded connection near an anti-node, but alternativecoupling arrangements can be employed.

Referring now to FIG. 4, an exploded view of the ultrasonic clampcoagulator apparatus 120 of the surgical system 10 in accordance with apreferred embodiment is illustrated. The proximal end of the ultrasonicclamp coagulator apparatus 120 preferably receives and is fitted to thedistal end of the ultrasonic drive unit 50 by insertion of the driveunit into the housing of the apparatus, as shown in FIG. 3. Theultrasonic clamp coagulator apparatus 120 is preferably attached to andremoved from the ultrasonic drive unit 50 as a unit. The ultrasonicclamp coagulator 120 may be disposed of after a single use.

The ultrasonic clamp coagulator apparatus 120 preferably includes ahandle assembly or a housing 130, preferably comprising mating housingportions 131, 132, and an elongated or endoscopic portion 150. When thepresent apparatus is configured for endoscopic use, the construction canbe dimensioned such that portion 150 has an outside diameter of about5.5 mm. The elongated portion 150 of the ultrasonic clamp coagulatorapparatus 120 extends orthogonally from the apparatus housing 130. Theelongated portion 150 can be selectively rotated with respect to thehousing 130 as further described below. The elongated portion 150preferably includes an outer tubular member or sheath 160, an innertubular actuating member 170, and the second acoustic portion of theacoustic system in the form of a waveguide 180 having an end-effector180'. As will be described, the outer sheath 160, the actuating member170, and the waveguide 180 are preferably joined together for indexedrotation as a unit (together with ultrasonic drive unit 50) relative tohousing 130.

As illustrated in FIG. 4, the proximal end of the waveguide 180 of thesecond acoustic portion is preferably detachably coupled to the mountingdevice 84 of the ultrasonic drive unit 50 near an anti-node as describedabove. The waveguide 180 preferably has a length substantially equal toan integer number of one-half system wavelengths (nλ/2). The waveguide180 is preferably fabricated from a solid core shaft constructed out ofmaterial which propagates ultrasonic energy efficiently, such astitanium alloy (i.e., Ti-6A1-4V) or an aluminum alloy. It iscontemplated that the waveguide 180 can alternatively be fabricated fromany other suitable material.

The waveguide is preferably substantially semi-flexible. It will berecognized that the waveguide can alternatively be substantially rigidor may comprise a flexible wire. The waveguide may be configured toamplify the mechanical vibrations transmitted through the waveguide tothe end-effector as is well known in the art. The waveguide may furtherhave features to control the gain of the longitudinal vibration alongthe waveguide and features to tune the waveguide to the resonantfrequency of the system.

It will be recognized that the waveguide 180 may have any suitablecross-sectional dimension. For example, the waveguide may have asubstantially uniform cross-section or the waveguide may be tapered atvarious sections or may be tapered along its entire length.

As shown in FIG. 4, the waveguide 180 generally has a first section 182,a second section 184, and a third section 186. The first section 182 ofthe waveguide extends distally from the proximal end of the waveguide,and has a substantially continuous cross-section dimension.

The first section 182 preferably includes at least one radial hole oraperture 188 extending diametrically therethrough, substantiallyperpendicular to the axis of the waveguide 180. The aperture 188 ispreferably positioned at a node, but may be otherwise positioned. Itwill be recognized that the aperture 188 may have any suitable depth andmay be any suitable shape. The aperture is configured to receive aconnector pin member which connects the waveguide 180, the tubularactuating member 170, and the tubular outer sheath 160 together forconjoint, indexed rotation relative to apparatus housing 130.

The second section 184 of the waveguide 180 extends distally from thefirst section 182. The second section 184 preferably also has asubstantially continuous cross-section. The diameter of the secondsection 184 is smaller than the diameter of the first section 182 andlarger than the diameter of the third section 186. As ultrasonic energypasses from the first section 182 of the waveguide 180 into the secondsection 184, the narrowing of the second section 184 will result in anincreased amplitude of the ultrasonic energy passing therethrough.

The third section 186 extends distally from the distal end of the secondsection 184. The third section 186 also has a substantially continuouscross-section. The third section 186 may also include small diameterchanges along its length. As ultrasonic energy passes from the secondsection 184 of the waveguide 180 into the third section 186, thenarrowing of the third section 186 will result in an increased amplitudeof the ultrasonic energy passing therethrough.

The third section 186 may have a plurality of grooves or notches (notshown) formed in its outer circumference. The grooves may be located atnodes of the waveguide 180 to act as alignment indicators for theinstallation of a damping sheath (not shown) and stabilizing siliconerings or compliant supports during manufacturing. A seal is preferablyprovided at the distal-most node, nearest the end-effector 180', toabate passage of tissue, blood, and other material in the region betweenthe waveguide and actuating member 170.

The end-effector 180' of the waveguide 180 is preferably integraltherewith and formed as a single unit. The end-effector may alternatelybe connected by a threaded connection, or by a welded joint. The distalend of the end-effector is disposed near an anti-node in order to tunethe acoustic assembly to a preferred resonant frequency f₀ when theacoustic assembly is not loaded by tissue. When the transducer assemblyis energized, the distal end of the end-effector is configured to movelongitudinally in the range of, for example, approximately 10-500microns peak-to-peak, and preferably in the range of about 10 to about100 microns at a predetermined vibrational frequency f₀.

In accordance with the illustrated embodiment, the end-effector 180',sometimes referred to as a blade, is preferably cylindrical forcooperation with the associated clamping mechanism of the present clampcoagulator apparatus. The end-effector may receive suitable surfacetreatment, as is known in the art.

With particular reference to FIG. 2, therein is illustrated the clampingmechanism of the present clamp coagulator 120, which is configured forcooperative action with the end-effector 180' of the waveguide 180. Theclamping mechanism includes a pivotally movable clamp arm 190, which ispivotally connected at the distal end thereof to the distal end of outertubular sheath 160. A clamp pad 192, preferably formed from Teflon orother suitable low-friction material, is mounted on the surface of theclamp arm for cooperation with the end-effector 180', with pivotalmovement of the clamp arm positioning the clamp pad in substantiallyparallel relationship to, and in contact with, the end-effector 180'. Bythis construction, tissue to be clamped is grasped between the pad 192and the end effector 180'. As illustrated, the pad 192 is preferablyprovided with a sawtooth-like configuration to enhance the gripping oftissue in cooperation with the end-effector 180'.

Pivotal movement of the clamp arm with respect to the end-effector iseffected by the provision of at least one, and preferably a pair oflever portions 193 of the clamp arm 190 at the proximal end thereof. Thelever portions are positioned on respective opposite sides of thewaveguide 180 and end-effector 180', and are in operative engagementwith a drive portion 194 of the reciprocable actuating member 170.Reciprocable movement of the actuating member, relative to the outertubular sheath 160 and the waveguide 180, thereby effects pivotalmovement of the clamp arm relative to the end-effector. The leverportions 193 can be respectively positioned in a pair of openingsdefined by the drive portion 194, or otherwise suitably mechanicallycoupled therewith, whereby reciprocable movement of the actuating memberacts through the drive portion 194 and lever portions 193 to pivot theclamp arm.

With particular reference to FIGS. 3, 5, and 6, reciprocable movement ofthe actuating member 170 is effected by the provision of a drive collar,generally designated 200, mounted on the proximal end of the actuatingmember for conjoint rotation. To this end, the drive collar includes apair of diametrically opposed axially extending arms 202 each having adrive lug 204, with the drive lugs being biased by the arms 202 intoengagement with suitable openings 206 defined by the proximal portion oftubular actuating member 170. Rotation of the drive collar 200 togetherwith the actuating member 170 is further effected by the provision of apair of keys 208 (see FIG. 8) diametrically engageable with suitableopenings 210 defined by the proximal end of the actuating member 170. Acircumferential groove 211 on the actuating member 170 receives onO-ring 211' (FIG. 4) for engagement with the inside surface of outersheath 160.

Rotation of the actuating member 170 together with tubular outer sheath160 and inner waveguide 180 is provided by a connector pin 212 extendingthrough these components of the apparatus. As illustrated in FIG. 4, thetubular actuating member 170 defines an elongated slot 214 through whichthe connector pin 212 extends to accommodate reciprocable movement ofthe actuating member relative to the outer tubular sheath and innerwaveguide.

A rotation knob 216 mounted on the outer tubular sheath facilitatesrotational positioning of the elongated portion 150 with respect to thehousing 130 of the clamp coagulator apparatus. Connector pin 212preferably joins knob 216 together with sheath 160, member 170, andwaveguide 180 for rotation as a unit relative to housing 130. In acurrent embodiment, hub portion 216' of the rotation knob acts torotatably mount the outer sheath 160, the actuating member 170, and thewaveguide 180 (as a unit with knob 216), on the housing 130.

In accordance with the present invention, the drive collar 200 providesa portion of the clamp drive mechanism of the apparatus which effectspivotal movement of the clamp arm 190 by reciprocation of actuatingmember 170. The clamp drive mechanism further includes a drive yoke 220which is operatively connected with an operating lever 222 of theapparatus, with the operating lever thus interconnected with thereciprocable actuating member 170 via drive yoke 220 and drive collar200. The operating lever 222 is pivotally connected to the housing 130of the apparatus (by a pivot mount 223) for cooperation in ascissors-like fashion with a handgrip portion 224 of the housing.Movement of lever 222 toward handgrip portion 224 translates actuatingmember 170 proximally, thereby pivoting clamp arm 190 towardend-effector 180'.

The drive yoke 220 is operatively connected with operating lever 222 sothat these components are normally pivotally movable, as a unit, about acommon pivot mount 223 of housing 130. In accordance with the presentinvention, force transmitted from the operating lever to the drive yokeis limited by an arrangement which permits relative movementtherebetween in opposition to a force-limiting spring. Theforce-limiting spring, designated 226, preferably comprises acompression coil spring which is arranged to operatively connect thedrive yoke 220 with the operating lever 222. Specifically, the driveyoke 220 includes a spring cage which defines a spring slot 228 withinwhich spring 226 is positioned in a pre-loaded condition. The operativeconnection of the operating lever and the drive yoke further comprisesat least one, and preferably a pair, of spring retainer flanges 230positioned on respective opposite sides of the spring cage (and springslot 228) of drive yoke 220. The spring slot 228 is thus positionedbetween the spring flanges 238 of this bifurcated portion of theoperating lever, with the pre-loaded spring 226 being held captivewithin the spring slot 228 defined by the drive yoke, and extendinglaterally thereof for positioning within openings respectively definedby the spring flanges 238. Thus, each spring flange is positionedadjacent to the spring cage of the drive yoke 220, with the springpositioned within the spring cage further being positioned within eachspring slot as defined by each spring flange 238.

As noted, the drive yoke 220 and operating lever 222 ordinarily arepivotally movable as a unit with respect to pivot mount 23 of housing130. However, the present force-limiting arrangement is configured suchthat the drive yoke 220 is pivotally movable with respect to springflanges 230 (about pivot mount 223) in opposition to the spring 226.This arrangement is achieved by having the spring bear against thesurfaces of the spring slots defined by each of the spring flanges 230,as the spring is held captive within the spring cage of the drive yoke.By this arrangement, force which is applied to the reciprocableactuating member 170 of the apparatus, by pivotal movement of operatinglever 222 acting through drive yoke 220 and drive collar 200, is limitedby the force with which spring 226 bears against the spring flanges 230.Application of excessive force results in pivotal displacement of springflanges 230 of the operating lever relative to drive yoke 220 inopposition to spring 226. When the force which is applied exceeds thepre-load limit of the spring 226, the operating lever 222 is pivotallymovable with respect to the drive yoke 220, in opposition to the spring.The operating lever can thus move independently from the drive yoke fora limited degree.

In a presently preferred embodiment, the spring rate of spring 226 isselected to provide a clamping force, between clamp arm 190 andend-effector 180', of preferably between about 1 pound and about 3.5pounds, measured at the middle of the clamp arm 190, and most preferablybetween about 2 pounds and 2.5 pounds. It will be appreciated thatdifferent shapes of the end-effector 180' and the clamp arm 190 candictate different operating ranges for optimal clamping forces, and thatdifferent excursions or frequency of operation may also mandatedifferent clamping force ranges.

As will be recognized, it can be desirable to limit the relativemovement between drive yoke 220 and operating lever 222 to avoid fullcompression of spring 226. To this end, the housing 130 of the apparatuspreferably includes at least one travel stop for operative engagementwith the operating lever 222, to thereby limit relative movement betweenthe operating lever 222 and drive yoke 220. As shown in FIGS. 9, 10, and11, housing portion 132 of the housing 130 includes a travel stop 232which is engageable with the operating lever 222 after a predetermineddegree of movement of operating lever 222 relative to drive yoke 220. Itis presently preferred that an additional travel stop (not numbered) beprovided on the apparatus housing for limiting movement of operatinglever 222 with respect to the drive yoke in an opposite direction, thatis, in a direction in which lever 222 is moved away from hand gripportion 224.

With further reference to FIGS. 9, 10, and 11, operation of the presentforce-limiting clamping mechanism is illustrated. As shown in FIG. 9,the present apparatus is illustrated in a configuration prior tooperation of the clamping mechanism. As will be observed, a dimension D₁shows the spacing between drive collar 220 and the associated rotationknob 216 fitted to the outside of outer tubular sheath 160.

FIG. 10 illustrates the position of operating lever 222 after theclamping mechanism has been moved through its maximum stroke, but priorto relative movement of lever 222 relative to drive yoke 220. As will beobserved, dimension D₂ shows that the actuating member (170) to whichdrive collar 220 is fixed has been withdrawn relative to rotation knob216 and the outer tubular sheath of the apparatus (thus closing clamparm 190). In this condition of the apparatus, operating lever 222 isspaced from hand grip portion 224 by a dimension S₁, with the lever 222spaced from travel stop 232.

Having reached the maximum displacement of drive collar 200 andactuating member 170 with respect to rotation knob 216 and outer tubularsheath 160, i.e., dimension D₂, application of further force to operatelever 222 results in pivotal movement of the operating lever withrespect to drive yoke 220, in opposition to spring 226. As will beobserved, operating lever 222 has moved to a relatively closer spacingto hand grip 224, dimension S₂, with FIG. 11 illustrating that theoperating lever has moved with respect to drive yoke 220. By virtue ofthis relative movement, in opposition to spring 226, minimal additionalforce is applied to drive collar 200 and actuating member 170.

FIG. 11 further illustrates engagement of operating lever 222 withtravel stop 232. Input of any additional force into the operating lever222 will not act to further relatively move the operating lever withrespect to drive yoke 220 (in opposition to spring 226). Thus, only apredetermined degree of relative movement is permitted between theoperating lever 222 and drive yoke 220 before the operating leverengages the travel stop 232. As noted, a similar limitation in thedegree of relative movement of these components is preferably achievedby the provision of another travel stop, on the housing 130 generally atthe rearward surface of operating lever 222, thus limiting relativedisplacement of the components when the operating lever 222 is moved ina direction to open clamp arm 190.

Thus, the clamp mechanism of the present apparatus includes aforce-limiting arrangement provided by the operative connection ofoperating lever 222 and spring yoke 220 by spring 226. The spring 226 ispreferably pre-loaded in position within the spring cage of the driveyoke, and the associated spring slots of the spring flanges 238, thusordinarily joining these components, under the influence of the springpre-load, to provide a relatively "stiff" connection therebetween. Byvirtue of this relatively stiff connection, a user of the apparatus isafforded good tactile feedback as the clamp arm 190 of the apparatus ispivotally moved by manipulation of the operating lever. In the eventthat excessive force is applied to the operating lever, the operatinglever is pivotally displaced with respect to the drive yoke, inopposition to spring 226. As described, operating lever 222 isengageable with travel stop 232 on the apparatus housing prior to fullcompression of the coil spring preferably provided in the drivemechanism. Notably, such relative displacement of the operating leverand drive yoke, and subsequent engagement with the travel stop, isreadily tactilely discemable by a user, thus signaling that maximumclamping force has been achieved.

Indexed rotational positioning of the elongated portion 150 of thepresent clamp coagulator apparatus 120 is provided by the provision of adetent mechanism incorporated into the clamp drive mechanism of theapparatus. Specifically, the drive collar 200 includes a pair of axiallyspaced apart drive flanges 232. A detent-receiving surface is providedbetween the drive flanges 232, and defines a plurality ofcircumferentially spaced teeth 234 which define detent-receivingdepressions generally about the periphery of the drive collar 200. In apresently preferred embodiment, twelve (12) of the teeth 234 areprovided, thereby providing indexed positioning of the elongated portion150 of the apparatus at 30° intervals relative to the housing 130 of theapparatus.

Indexed rotational movement is further achieved by the provision of atleast one, and preferably a pair, of diametrically opposed detents 236respectively provided on cantilevered yoke arms 238 of drive yoke 220.By this arrangement, the yoke arms 238 are positioned between the driveflanges 232 for engagement with the confronting surfaces thereof, andbias the detents 236 into engagement with the drive collar 200. Indexedrelative rotation is thus achieved, with the detents 236 of the yokearms cooperating with the drive flanges 238 for effecting reciprocationof the actuating member 170. In a presently preferred embodiment, thedrive yoke 220 is formed from suitable polymeric material, with thebiasing force created by the yoke arms acting on the detents thereofcooperating with the radial depressions defined by the drive collar toresist relative rotational torque less than about 5 to 20 inch-ounces.As such, the elongated portion 150 of the clamp coagulator apparatus ismaintained in any of its selected indexed rotational positions, relativeto housing 130, unless a torque is applied (such as by rotation knob216) exceeding this predetermined torque level. A snap-like indexingaction is thus provided.

Rotation of the elongated proportion 150 of the present clamp coagulatorapparatus 120 is preferably effected together with relative rotationalmovement of ultrasonic drive unit 50 with respect to apparatus housing130. In order to join the elongated portion 150 to the ultrasonic driveunit 50 in ultrasonic-transmitting relationship, the proximal portion ofthe outer tubular sheath 160 is preferably provided with a pair ofwrench flats 240 (see FIG. 4). The wrench flats allow torque to beapplied by a suitable torque wrench or the like to thereby permit thewaveguide 180 to be joined to the ultrasonic drive unit 50. Theultrasonic drive unit, as well as the elongated portion 150, are thusrotatable, as a unit, by suitable manipulation of rotation knob 216,relative to housing 130 of the apparatus. The interior of housing 130 isdimensioned to accommodate such relative rotation of the drive unit 50.

Thus, the present surgical clamp coagulator apparatus is configured forhighly efficient and versatile use, with the construction beingsufficiently straight-forward and economical in configuration to permitsingle-patient use. Components of the apparatus can be fabricated frommaterials suited for surgical applications. By virtue of the detentmechanism provided by cooperation of drive collar 200 and drive yoke220, selective angular positioning of the elongated portion 150 of theapparatus, and the associated ultrasonic drive unit 50, is readilyeffected with respect to the housing 130 of the apparatus. Thescissors-like action provided by pivotal operating lever 222 andcooperating handgrip portion 224 facilitates convenient and efficientmanipulation and positioning of the apparatus, and operation of theclamping mechanism at the distal portion of the apparatus whereby tissueis efficiently urged against the end-effector 180'. The detent mechanismresists rotation of the ultrasonic drive unit, and associated cableassembly, with respect to the housing 130 with the resistence torotation readily and conveniently overcome by application of sufficienttorque via rotation knob 216.

From the foregoing, it will be observed that numerous modifications andvariations can be effected without departing from the true spirit andscope of the novel concept of the present invention. It is to beunderstood that no limitation with respect to the specific embodimentillustrated herein is intended or should be inferred. The disclosure isintended to cover, by the appended claims, all such modifications asfall within the scope of the claims.

What is claimed is:
 1. An ultrasonic surgical clamp apparatuscomprising:a housing; an outer tubular sheath having a proximal endjoined to said housing, and a distal end; an inner actuating memberreciprocably positioned within said outer tubular sheath; an ultrasonicwaveguide positioned within said outer tubular sheath and having anend-effector extending distally of said distal end of said outer tubularsheath; a clamp arm pivotally mounted on said distal end of said outertubular sheath for pivotal movement with respect to said end-effectorfor clamping tissue between said clamp arm and said end-effector, saidclamp arm being operatively connected to said actuating member so thatreciprocable movement of said actuating member pivotally moves saidclamp arm with respect to said end-effector; an operating leverpivotally mounted on said housing for pivotal movement relative to alever pivot axis, and a clamp drive mechanism interconnecting saidoperating lever with said actuating member so that pivotal movement ofsaid operating lever reciprocably moves said actuating member forpivotally moving said clamp arm, said clamp drive mechanism including areciprocably movable drive collar joined to said actuating member forreciprocable movement therewith relative to said outer tubular sheath,and a drive yoke operatively joined to said operating lever for movementrelative to said lever pivot axis, said drive yoke engaging said drivecollar so that pivotal movement of said operating lever and said driveyoke reciprocably moves said drive collar and said inner actuatingmember, one of said operating lever and said drive yoke defining aspring cage, and the other defining a spring slot positioned adjacent tosaid spring cage, with a spring held captive within said spring cagepositioned within said spring slot to transmit and limit forcetransmitted from said operating lever to said drive yoke by movement ofsaid operating lever relative to said drive yoke in opposition to saidspring.
 2. An ultrasonic clamp apparatus in accordance with claim 1,whereinsaid operating lever includes a bifurcated portion having a pairof spring flanges each defining one of said spring slots, said springcage being provided on said drive yoke and being positioned between saidpair of spring flanges.
 3. An ultrasonic clamp apparatus in accordancewith claim 1, whereinsaid housing includes at least one travel stop tolimit pivotal movement of said operating lever relative to said housing.4. An ultrasonic clamp apparatus in accordance with claim 1, whereinsaidspring comprises a compression coil spring.
 5. An ultrasonic surgicalclamp apparatus comprising:a housing; an outer tubular sheath having aproximal end rotatably joined to said housing, and a distal end; arotation knob mounted on said outer sheath for effecting rotationthereof with respect to said housing; an inner tubular actuating memberreciprocably positioned within said outer tubular sheath for rotationtherewith with respect to said housing; an ultrasonic waveguidepositioned within said outer tubular sheath and having an end-effectorextending distally of said distal end of said outer tubular sheath; aclamp arm pivotally mounted on said distal end of said outer tubularsheath for pivotal movement with respect to said end-effector forclamping tissue between said clamp arm and said end-effector, said clamparm being operatively connected to said actuating member so thatreciprocable movement of said actuating member pivotally moves saidclamp arm with respect to said end-effector; an operating leverpivotally mounted on said housing on a housing pivot, and a clamp drivemechanism interconnecting said operating lever with said actuatingmember so that pivotal movement of said operating lever reciprocablymoves said actuating member for pivotally moving said clamp arm; saidclamp drive mechanism including a reciprocably movable drive collarjoined to said actuating member for conjoint rotation and forreciprocable movement therewith relative to said outer tubular sheath,and a drive yoke operatively joined to said operating lever whichengages said drive collar while permitting relative rotationtherebetween, said drive yoke being pivoted about said housing pivot toreciprocably move said drive collar and said actuating member, aforce-limiting spring operatively interconnecting said drive yoke andsaid operating lever to limit force transmitted therebetween by movementof said operating lever relative to said drive yoke in opposition tosaid force-limiting spring, said housing including a travel stopengageable by said operating lever after a predetermined degree ofmovement of said operating lever relative to said drive yoke.
 6. Anultrasonic clamp apparatus in accordance with claim 5, whereinsaidspring comprises a compression coil spring, said operating lever beingengageable with said travel stop prior to full compression of said coilspring.
 7. An ultrasonic clamp apparatus in accordance with claim 5,whereinsaid drive yoke includes a spring cage within which said springis positioned, said operating lever including at least one spring flangepositioned adjacent to said spring cage and defining a spring slotwithin which said spring is further positioned.
 8. An ultrasonic clampapparatus in accordance with claim 7, whereinsaid operating leverincludes a bifurcated portion having a pair of said spring flangespositioned adjacent to and on respective opposite sides of said springcage, said spring being positioned with a spring slot defined by each ofsaid spring flanges.